INTERREG MICRO PROJECT

Uptake and retention of microplastics by the shore crab Carcinus maenas

Microplastics, plastics particles <5mm in length, are a widespread pollutant of the marine environment. Oral ingestion of microplastics has been reported for a wide range of marine biota, but uptake into the body by other routes has received less attention. Here, we test the hypothesis that the shore crab (Carcinus maenas) can take up microplastics through inspiration across the gills as well as ingestion of pre-exposed food (common mussel Mytilus edulis). We used fluorescently labelled polystyrene microspheres (8-10 μm) to show that ingested microspheres were retained within the body tissues of the crabs for up to 14 days following ingestion and up to 21 days following inspiration across the gill, with uptake significantly higher into the posterior versus anterior gills. Multi-photon imaging suggested that most microspheres were retained in the foregut after dietary exposure due to adherence to the hair like setae and were found on the external surface of gills following aqueous exposures. Results were used to construct a simple conceptual model of particle flow for the gills and the gut. These results identify ventilation as a route of uptake of microplastics into a common marine non-filter feeding species.